Bleaching fiber



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Patented Feb. 8, 1938 UNITED STATES PATENT OFFICE BLEACHING FIBER Hans0. Kauffmann, Bufialo, N. Y., assignor to Buffalo Electro-ChemicalCompany, Inc.,

Buffalo, N. Y.

No Drawing. Application March 8, 1934, Serial No. 714,735

3 Claims.

The present invention relates to a method of bleaching natural andartificial fibers and/or filaments and more particularly to a method ofbleaching such fibers and/ or filaments with alkaline solutionscontaining hydrogen peroxide at room temperature.

Heretofore it has been deemed necessary to subject natural or artificialfibers toimmersion in peroxide in bleaching processes in order to effectthe desired results, necessitating the use of vari ous bleachingsolutions, addition of compounds to the bath, expensive and cumbersomeapparatus and usually prolonged heating.

In my present invention I am able to bleach either animal or vegetablefibers readily and expeditiously with a minimum of equipment and withoutthe necessity of prolonged immersion or heating. The bleached fibersobtained are of an exceptional whiteness, possess in most cases enhancedphysical properties such as greater tensile strength, better handle andfreedom from injury or tenderness. In the treatment of certain classesof fibers, they are left in excellent condition heretofore thoughtimpossible on a practical scale since the action of the bleachingsolution is efiected at normal or room temperatures and this eliminatesthe catalytic effects which take place at elevated temperatures inperoxide solutions.

In accordance with my invention, the goods after they have beenpreliminarily cleaned or treated according to the usual known practicesas for instance souring, scouring, desizing, boiling, desulphurizing,degumming or other usual preliminary cleaning actions, or preliminarilytreated with alkalineor acid hypochlorite solutions, alkaline or acidsulphit'e solutions, hydrosulphites, permanganates, chromates,chlorates, and similar oxidizing or reducing agents, are treated with analkaline solution of hydrogen peroxide at room or normal temperature byany method whereby the fabric or fiber whether as raw stock, carded,spun, woven, knitted or felted, is thoroughly wet out or saturated withthe desired bleaching solution. This step will usually include asaturation of the goods, such as by immersion or immersions in thebleaching solution, and an elimination of the surplus bleaching solutionabove that necessary to saturate the same by any well known means as forinstance by squeezing or hydroextracting or by any known device ormethod, or the goods are saturated by any other convenient methods andpermitted to stand in the saturated condition until the desired bleachedresult is obtained. This desired bleached condition is obtained after aperiod of from several minutes or up to 24 hours or more whereupon thegoods are rinsed or the residual solution otherwise removed. It will, ofcourse, be understood that the surplus bleaching. solution squeezed orhydroextracted from the goods may be returned to the main bulk of thebleaching solution and thereafter used to bleach further batches ofgoods.

To those who are acquainted with bleaching procedures, it will beunderstood that in some cases a preliminary treatment of the fiber isnot necessary, as my process will be effective on fibers as they appearnaturally or come from certain manufacturing processes without thepreliminary cleaning or chemical treatment.

A composition of bath which I have found effective in bleaching animalfibers or filaments,

whether in the raw state or as prepared goods," contains an alkali inaddition to water and hydrogen peroxide. This alkali may includematerials acting as stabilizers for the hydrogen peroxide solution andmay include, among others, silicates of soda, phosphates such as sodiumpyro-phosphate, tri-sodium phosphate, di-sodium phosphate,sodium-bicarbonate and borax. It will, of course, be understood thatadditional chemicals or stabilizers, not necessarily alkaline incharacter, may be added to the bath, and other alkaline materials usedto obtain the desired alkalinity of the solution. These may include thematerials mentioned above as well as the usual and well known alkalinesubstances used in bleaching operations such as caustic soda, soda ash,ammonia, etc. Depending upon the type of goods, their previous treatmentand history, bleaching assistants may also be included in the bath andamong them may be mentioned soaps, sulphonated oils, solvents of variouskinds and wetting-on agents.

As a typical example of a solution suitable for bleaching animal,vegetable or artificial fibers, I have effectively bleached such fiberswith a formulated solution containing:

Water gals 9O Silicate of soda 42 B lbs 5 to 25 Hydrogen peroxide,volume gals 10 The hydrogen peroxide used in the above formula is acommercial product wherein one volume of the hydrogen peroxide will,upon decomposition into water and oxygen, produce one hundred.

at time volumes of oxygen gas at standard temperature and pressure.

The goods are saturated with the bleaching solution, the surplusbleaching solution above that necessary to saturate the goods is removedand the goods permitted to stand in the saturated condition until thedesired degree of bleaching is effected. I have found that piece goodsmay be eifectively bleached after saturation by winding them upon rolls.The saturated goods may be stacked, piled or stored in any convenientmanner in a box, bin or movable container or even on the floor of or inany suitable chamber.

Effective hydrogen peroxide bleaching is very often obtained inaccordance with my invention by subjecting the goods to a doubletreatment. This is more particularly true in those cases where yarn istreated which would, in accordance with the older and well known methodsof bleaching require a double hydrogen peroxide boil such as is done inthe bleaching of certain types of cotton yarn.

The first steep is carried out with a solution containing, as anexample:

In 1000 cos. or 1 liter of the aqueous solution Caustic soda gs 10Silicate of soda (42 B.) ccs 30 Hydrogen peroxide 100 volume ccs 20 Thegoods are saturated with this bleaching solution, the excess of thesolution expressed or eliminated whereby the goods retain from 50 to130% or more of their original weight, or the goods saturated by anyother convenient method. They are then permitted to stand in thissaturated condition from 8 to 16 hours, although the time may fallwithout these limits depending upon the type of goods, concentration ofthe chemicals in the solution, then rinsed and subjected to a secondsteep in a solution of the following composition:

Caustic soda gs 20 Silicate of soda (42 B.) ccs 60 Hydrogen peroxide 100volume ccs 40 Water to make 1000 cos. of solution The goods aresaturated and treated in a manner similar to that described for thefirst steep, the steeping operation requiring 2 to 12 hours. The goodsare then thoroughly rinsed with water and dried and finished in theusual manner.

In many cases where the cotton contains a considerable amount ofimpurities such as motes, cotton seeds, stains, dirt and otherundesirable foreign matter, it is advisable to boil the goods at firsteither at an atmospheric or higher pressure with alkaline solutions inthe usual way. It is also advisable sometimes, especially in cases.Where the goods contain a considerable amount of size, to remove thesize according to one of the usual methods. Preliminary treatment withwetting-out agents which might be used in the boil will help to producea more even and uniform result on the goods when they are subse quentlybleached by my method.

My process is adaptable for use in bleaching goods containing coloredportions (cotton, linen, etc.). I have found in practical operation thatif the goods are given one or more treatments with a solution of thecomposition described above the danger of bleeding or fading of colorsis very considerably minimized.

Goods which have been mercerized may be bleached by my process withoutremoving caustic soda remaining in the goods after they come from themercerizing machines. eliminate the usual souring of such goods.

In case of linen, ramie, jute, artificial silk and The process is alsoadaptable to bleaching of wood and other pulp such as is used in thepaper or related industries. It also is suitable for bleaching unifiedartificial products made or manufactured from vegetable or related materials, such as cellophane, nitrocellulose. collodion 4 V i and others.

In the bleaching of wool, as for instance wool top, the top, whetherscoured or unscoured, is saturated with a suitable peroxide bleachingsolution, the surplus removed, as for example by hydro-extraction, andthe saturated top allowed to bleach at room temperature until thedesired shade is obtained which may require from several minutes toseveral hours depending upon the character of the wool and its previoustreatment and on the type and concentration of bleaching solution. Inthe case of wool I have found it advantageous to use a bleachingsolution made in accordance with the following composition which isillustrative and not limitative. It will be understood that any alkalisor combinations of alkalis that do not render the solution so alkalineas to tender or yellow the goods may be used.

Water gals Pyrophosphate lbs 2 to 10 Ammonia (aqueous) lbs 2 to 10volume peroxide gals 10 I have found that very effective bleaching isobtained upon real silks, mohairs, alpaca, camel hairs, in fact allanimal fibers, by subjecting to the same treatment and bleachingsolution as described above for W001. It will, of course, be understoodthat goods containing mixtures of any of the above fibers such as silkand cotton, silk and wool and others can be treated by my process toproduce similar excellent results.

From the results of my experiments, I have found that variations instrength and concentration of the added chemical may be made over arather wide range depending upon the type of goods being treated andupon their previous history and treatment. In general, where theconcentration of the alkaline materials is increased above thosequantities given in the examples, less hydrogen peroxide need be usedand vice versa. Further, it will be understood that although I havespecifically illustrated the improved bleaching process by mentioninghydrogen peroxide, I have found that certain other chemicals-developingactive oxygen in such solutions may be used by making the propersubstitution, due regard being had for the quantity of available oxygen;as materials suitable for such substitution I may mention sodiumperoxide and the per salts such as perborates, per carbonates, persilicates and persulfates among others. It will be noted that I haveillustrated bleaching solutionsso high in alkalinity and peroxide thatwere such solutions used in the present methods of bleaching animal andvegetable fibers such fibers would be injured to such an extent as torender them This will also I (JELNT CHEWCAL MODIFL CATION OF TEXTiLES &FIBERS,

commercially valueless if they are not actually destroyed. Prolongedcirculation of such solutions over or contact of the goods withsolutions of the high concentrations that I recommend is to be avoidedas by saturating the goods to produce the damp condition, I havesufficient active bleaching solution in contact therewith to carry thebleaching action to the desired point at room temperature without thedangers to which excess of such reagents would subject the fibers.

The term room temperature is used herein to describe a range oftemperature normally encountered in a plant and may be as high as 115 F.Where such high temperatures are en countered, the time of steeping willbe less than that required at lower temperatures in order to obtain afull or standard white.

In all bleaching operations, the most difficult and dangerous problem isthat of obtaining the maximum whiteness without injury to the fibers.Thus where it is desired to obtain a full white or complete bleach, sayfor instance a 100% bleach, it is usually rather a simple problem,irrespective of the method of bleaching used to obtain a bleach; thereal diificulty is to effect the last 25% action to get the bleachwithout damaging the goods. By my method, full bleaching to efiect the100% bleach is obtainable readily in a few hours without the necessityof using heat during the bleaching action or of using expensive liquidcirculating apparatus.

Where the term high concentration of peroxide is used in the claims, aconcentration of peroxide is meant wherein the amount of persearchtiooa.

oxide, calculated as hydrogen peroxide, is greater than about 1% ofhydrogen peroxide.

The term moist condition or damp condition as used in the claims means acondition Where the goods contain at least 50% by weight of liquid butare not immersed in the liquid.

I claim:

1. The process of bleaching goods of the group consisting of artificial,animal and vegetable fibers which comprises saturating the fibers with ableaching solution comprising a high concentration of peroxide,eliminating the excess of the bleaching solution from the fibers so thatthe goods are damp, thereafter stacking the goods to maintain the fibersdamp, and permitting the fibers to bleach in the damp condition.

2. The process of bleaching goods of the group consisting of artificial,animal and vegetable fibers which comprises incorporating sufiicientbleaching solution containing a high concentration of peroxide in thefibers to render the same damp, thereafter stacking the goods tomaintain the fibers damp and permitting the fibers to bleach in the dampcondition.

3. The process of bleaching goods of the group consisting of artificial,animal and vegetable fibers which comprises incorporating sufiicientbleaching solution containing a high concentration of peroxide in thefibers to render the same damp, thereafter stacking the goods tomaintain the same moist but out of contact of additional bleachingsolution and permitting the fibers to bleach in the damp condition.

HANS O. KAUFFMANN.

